Bill we moved your post to start a new topic as this is something that I've been seeing the last year and it seemed more fitting. As you guys know, we used to have a gigantic urchin population down here in so cal, it was so bad you couldn't walk around on a low tide entry without seeing them or getting some in you. The urchins killed off a lot of the kelp, much like they are doing up in nor cal probably. Combined with the huge storms, kelp really didn't have a chance to come back.
There is a lot of debate at whether or not the kelp growing had anything to do with the reseeding project that the kelp restoration group did, IMO it didn't do a lot and most of it came back on it's own. The only reason I feel this way is because a lot of kelp beds came back at the same time all along the coast, much of these areas are also areas that were not touched by the kelp replenishment. At the same time some organizations were doing purple urchin smashing and while this kills the host urchin, I'm not too sure how the larvae settlement is affected as smashing urchins may release eggs/sperm that get fertilized and move down the coast to settle.
IMO and a lot of other guys opinion at the aquarium is that most of the urchin died off around so cal because the seastar wasting disease moved from large seastars, to bat stars, and eventually to urchins. There's no data to back this up but we saw a lot of urchins lose spines during some sort of infection and the die off occurred all over the place to where there are hardly any purple urchins around in the shallows. It could be it was a combination of effects like starvation leading to susceptibility to disease. Hopefully that happens again up north where the ab beds are.
The article does show that the seastar population is rebounding and we see this as well during our collection dives, there's not a ton of seastars like there were pre disease, but for a while we weren't seeing even a single seastar and now we'll see about a hundred of certain species in a dive. The surviving seastars aren't babies that grew up, they are adults that hid out and got exposed or mildly infected and made it back.
The disease isn't over yet, occasionly we'll see a few get it in our tanks, but we have a treatment for it and usually the seastars do well if we get it right away.